Understanding the function of poplar species under different irrigation regimes is critical for water resources and ecosystem sustainable management. This study was conducted in order to understand the performance (survival and height growth) of two poplar species (Populus alba L. and Populus caspica Bornm.) cuttings in two lengths (15 cm and 25 cm) under three irrigation treatments (7-day, 14-day and 21-day intervals). One trial was established using split-split-plot design with three replications. Every two weeks height and number of remaining cuttings were measured. Results showed the survival average at the end of periods for 7-day, 14-day and 21-day irrigation treatments were 83.33 %, 22.08 % and 0 %, respectively, for P. alba and P. caspica were 25.89 % and 44.39 %, respectively and for cuttings in 15 and 25 cm were 29.61 % and 40.66 % respectively. The results of two-way analysis of variance of the survival among cuttings indicated that the differences survival among cuttings were all marked under the four treatments and analysis of variance of the height growth indicated that except under the size treatment, the differences height growth among cuttings were all marked under the other three treatments.

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Oriental beech established in the Hyrcanian forests, is a valuable tree whose habitats are constantly exposed to destructive factors which change the nutritional status of soil and leaves. Analysis of foliar elements is a commonly used method for studying tree nutrient status that indicates site's quality. Foliar analysis of beech (Fagus orientalis Lipsky) was carried out in Kojour (Mazandaran) in order to assess the nutritional balance of trees in a damaged forest site (a direct result of livestock grazing and anthropogenic perturbations). Sunny leaves of dominant trees were taken in August and foliar concentration of macroelements, N, P, Ca, K and Mg were measured. The diagnosis and recommendation integrated system (DRIS) analysis was applied for evaluating the nutritional state. The results showed deficiency with K and P in disturbed stands. Nutrient Balance Index (NBI) indicated imbalance in nutrient status. These results suggest the usefulness of DRIS for foliar tissue analysis as an indicator of nutritional status and elemental stress in natural forests.

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